Generally, fiber-reinforced plastic members have been used in vehicles as a structural objects that constitute vehicle bodies. Fiber-reinforced plastic members have been essentially used to absorb the energy of external impacts in order to ensure the safety of passengers in the vehicle interior in the event of a collision, and to have different strengths in different areas in order to withstand the damage caused by impacts.
Accordingly, technologies for satisfying the requirement for performance that differs by area have been extensively used, and have been characterized by employing metal members prepared through local softening, hot stamping, or the like.
The requirement for a vehicle body to exhibit different strengths in different areas and to be lightweight may be achieved by adopting a fiber-reinforced plastic composite composed of a synthetic resin and reinforcement fibers embedded in the synthetic resin, which can have a higher strength in the direction in which the reinforcement fibers extend and is lighter than general metals, or by bonding the fiber-reinforced plastic composite to a metal member to realize a composite member having a desired shape.
The general fiber-reinforced plastic composite composed of reinforcement fibers may be produced through a resin transfer molding (RTM) process. The RTM process is carried out in such a way as to dispose fiber mesh plates, which have been previously prepared, in a metal mold and to impregnate the mesh plates with synthetic resin, thus providing a fiber-reinforced plastic composite. Alternatively, the RTM process may be carried out in such a way as to layer fiber mesh plates impregnated with synthetic resin on each other.
In the case of producing a fiber-reinforced plastic composite including reinforcement fibers through an RTM process, the requirement may be satisfied to exhibit different strengths in different areas by orienting fiber mesh plates such that reinforcement fibers of the oriented fiber mesh plates can exert the required strengths, or by adjusting the number of reinforcement fiber mesh plates in respective areas.
In a certain example, a Korean conventional art has disclosed a method of producing cross member for commercial vehicle.
However, among such processes of producing a fiber-reinforced plastic composite, the process of layering reinforcement fiber mesh plates such that the directions of the respective reinforcement fiber mesh plates are different from each other may have disadvantageous. For example, it is difficult to progressively change the strengths in different area as required, and efficient transmission of stress may be not realized due to the presence of disconnected portions between reinforcement fibers. Accordingly, the number of reinforcement fiber mesh plates has to be increased in order to satisfy the required strengths, which is inefficient. Furthermore, since impregnating the reinforcement fiber mesh plates, disposed in a mold, with synthetic resin must be fulfilled through an additional procedure, the number of processes may be disadvantageously increased.
The information disclosed in this section are merely for the enhancement of understanding of the general background of the invention, and should not be taken as an acknowledgment or any form of suggestion that the matters form the related art already known to a person skilled in the art.